same thing
I had the X for two weeks and then traded it in for a Droid 2. That really surprised the VZW dude, he was like " why would you do that?" but the answer was simple, I live on the road and much prefer real keys to type email on. Plus the X is a monster sized phone, I like to carry mine in a hip case not in my pocket and when you put that X in a case and clip it to your belt it looks like an iPad, I just couldn't take those "you are such a nerd" stare downs.
The two phones are identical in terms of the OS, or will be when the X finally gets an upgrade to the current version of Android. The screen is 4.3 vs. 3.7 and the D2 has the slider but everything else, cpu performance, video performance, screen quality, all the same. The X has a bigger screen but gives up on dpi because of that so the size advantage does not translate to more on the screen. The X does have a higher rez camera and takes higher rez video which is a big deal to some. Personally I can't tell a lot of differences in the still or video shots I've done on either phone, both are OK but not among the best camera phones.